The objective of the nonhuman primate core is to provide highly integrated clinical management and laboratory investigations using nonhuman primate models of AIDS for vaccine development. The Core will enhance and facilitate the ability of investigators to perform studies in nonhuman primates. The core consists of clinical and laboratory components. The clinical component will acquire, house and care for the nonhuman primates and perform pathogenicity, immunogenicity and efficacy studies using different combinations of the most promising NSV vectors from murine studies. The core will also be responsible for the daily clinical care of animals and animal procedures such as immunizing the animals, blood draws, fluid collection (nasal, oral and rectal secretions), biopsies, etc. The laboratory component of the core will perform routine hematology, clinical chemistry, ova and parasite examination of feces, microbiology, and pathologic examination of all necropsies and biopsies in support of the animal studies. The core will also provide flow cytometry and cellular immunology services, viral stocks of SIV, and specialized pathology services including in situ hybridization, immunohistochemistry, confocal microscopy and image analysis. The specific aims of the core are: 1. Provide expertise and assistance in the design and implementation of experiments using nonhuman primates. 2. Perform in vivo pathogenicty and initial immunogenicity studies of NDV-based vaccine vectors in rhesus macaques. 3. Study the efficacy of optimized viral RV.^NDV and VSV vectors in the rhesus/SiV challenge system RELEVANCE (See instructions): Nonhuman primates are a necessary part of development of vaccines to prevent AIDS.